target/arm: Convert Neon 2-reg-scalar float multiplies to decodetree

target/arm: Convert Neon 2-reg-scalar float multiplies to decodetree

Convert the float versions of VMLA, VMLS and VMUL in the Neon
2-reg-scalar group to decodetree.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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As noted in the comment on the WRAP_FP_FN macro, we could have
had a do_2scalar_fp() function, but for 3 insns it seemed
simpler to just do the wrapping to get hold of the fpstatus ptr.
(These are the only fp insns in the group.)
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>